Bottom Line:
Phylogenetically, highest similarity was to Streptomyces misionensis NBRC 13063(T) (99.6%) along with two other strains (>98.9% sequence similarities).The DNA-DNA relatedness between MUSC 136(T) and these type strains ranged from 22.7 ± 0.5% to 46.5 ± 0.2%.It was also found to possess high cytotoxic effect against HCT-116 cells, which probably mediated through altering p53 protein and intracellular glutathione levels.

ABSTRACTActinobacteria from the unique intertidal ecosystem of the mangroves are known to produce novel, bioactive secondary metabolites. A novel strain known as MUSC 136(T) (=DSM 100712(T) = MCCC 1K01246(T)) which was isolated from Malaysian mangrove forest soil has proven to be no exception. Assessed by a polyphasic approach, its taxonomy showed a range of phylogenetic and chemotaxonomic properties consistent with the genus of Streptomyces. Phylogenetically, highest similarity was to Streptomyces misionensis NBRC 13063(T) (99.6%) along with two other strains (>98.9% sequence similarities). The DNA-DNA relatedness between MUSC 136(T) and these type strains ranged from 22.7 ± 0.5% to 46.5 ± 0.2%. Overall, polyphasic approach studies indicated this strain represents a novel species, for which the name Streptomyces malaysiense sp. nov. is proposed. The potential bioactivities of this strain were explored by means of antioxidant and cytotoxic assays. Intriguingly, MUSC 136(T) exhibited strong antioxidative activities as evaluated by a panel of antioxidant assays. It was also found to possess high cytotoxic effect against HCT-116 cells, which probably mediated through altering p53 protein and intracellular glutathione levels. Chemical analysis of the extract using GC-MS further affirms that the strain produces chemopreventive related metabolites.

f2: Neighbour-joining phylogenetic tree based on almost complete 16S rRNA sequences (1489 nucleotides) showing the relationship between strain MUSC 136T and representatives of some other related taxa.Numbers at nodes indicate percentages of 1000 bootstrap re-samplings, only values above 50% are shown. Bar, 0.005 substitutions per site. Asterisks indicate that the corresponding nodes were also recovered using the maximum-likelihood tree-making algorithm. Streptacidiphilus albus NBRC 100918T was used as an outgroup.

f2: Neighbour-joining phylogenetic tree based on almost complete 16S rRNA sequences (1489 nucleotides) showing the relationship between strain MUSC 136T and representatives of some other related taxa.Numbers at nodes indicate percentages of 1000 bootstrap re-samplings, only values above 50% are shown. Bar, 0.005 substitutions per site. Asterisks indicate that the corresponding nodes were also recovered using the maximum-likelihood tree-making algorithm. Streptacidiphilus albus NBRC 100918T was used as an outgroup.

Bottom Line:
Phylogenetically, highest similarity was to Streptomyces misionensis NBRC 13063(T) (99.6%) along with two other strains (>98.9% sequence similarities).The DNA-DNA relatedness between MUSC 136(T) and these type strains ranged from 22.7 ± 0.5% to 46.5 ± 0.2%.It was also found to possess high cytotoxic effect against HCT-116 cells, which probably mediated through altering p53 protein and intracellular glutathione levels.

ABSTRACTActinobacteria from the unique intertidal ecosystem of the mangroves are known to produce novel, bioactive secondary metabolites. A novel strain known as MUSC 136(T) (=DSM 100712(T) = MCCC 1K01246(T)) which was isolated from Malaysian mangrove forest soil has proven to be no exception. Assessed by a polyphasic approach, its taxonomy showed a range of phylogenetic and chemotaxonomic properties consistent with the genus of Streptomyces. Phylogenetically, highest similarity was to Streptomyces misionensis NBRC 13063(T) (99.6%) along with two other strains (>98.9% sequence similarities). The DNA-DNA relatedness between MUSC 136(T) and these type strains ranged from 22.7 ± 0.5% to 46.5 ± 0.2%. Overall, polyphasic approach studies indicated this strain represents a novel species, for which the name Streptomyces malaysiense sp. nov. is proposed. The potential bioactivities of this strain were explored by means of antioxidant and cytotoxic assays. Intriguingly, MUSC 136(T) exhibited strong antioxidative activities as evaluated by a panel of antioxidant assays. It was also found to possess high cytotoxic effect against HCT-116 cells, which probably mediated through altering p53 protein and intracellular glutathione levels. Chemical analysis of the extract using GC-MS further affirms that the strain produces chemopreventive related metabolites.